Ferrofluids and magnetism in the oil industry: Theories, challenges, and current applications—A comprehensive review

This review aims to contextualize the prospective integration of ferrofluid technologies into two critical oil macro-processes: recovery and transportation, both fundamental components of the oil supply chain. The initial section explores the research content and emerging trends associated with this technology by conducting a bibliometric analysis to highlight its advancements, drawbacks, and potential within the oil industry. The subsequent section discusses the most relevant theoretical aspects of ferrofluids, with a particular emphasis on stability, which is a pivotal yet insufficiently investigated aspect in the context of nanoparticle technologies in oil recovery and transportation. Furthermore, we present an overview of the magnetic properties, constitutive equations of ferrohydrodynamics, and magnetoviscous effects that elucidate the diverse rheological behaviors induced in ferrofluids by the action of uniform and oscillating magnetic field configurations. Against this background, subsequent sections summarize some selected experimental approaches conducted in systems that closely replicate real-world scenarios. These include the physiochemical interactions between ferrofluids and crude oils under the influence of external magnetic fields and thermodynamic flow conditions, such as those observed in reservoir environments. The review concludes with a section dedicated to the flow of ferrofluids in pipelines, highlighting experimental results under the influence of magnetic field configurations that induce reductions in viscosity, as well as alternative non-conventional applications associated with core annular flows. This comprehensive overview aims to provide an objective vision of the potential of ferrofluid technologies in enhancing the efficiency and effectiveness of multiple processes in the oil industry.